Go here to view the sheet music for this song," The 1-1-1 Spelling Rule"

LEARN THE RULE

hop + ing

Check the root word.(hop) Ask yourself, "Does the root word have one syllable?" (yes)
"Does it have one vowel?" (yes, o)
"Does it have one consonant at the end?" (yes, p)
Since you can see all these things, you must double the "p" before adding a
suffix such as ed, er, est, or ing (suffixes which begin with a vowel).

hop + ing = hopping
hop + er = hopper
hop + ed = hopped

cook + ing

Check the root word.(cook) "Does the word have one syllable?" (yes)
"Does it have one vowel?" (NO! It has oo.)
This is not a 1-1-1 word. Just add the suffix without doubling the
last consonant.

cook + ing = cooking
cook + er = cooker
cook + ed = cooked

list + ed

Check the root word.(list) "Does it have one syllable?" (yes)
"Does it have one vowel?" (yes, i)
"Does it have one consonant at the end?" (NO! It has two, s and t)
"List" is not a 1-1-1 word. Do not double the last consonant before
adding "ed" or "ing" as a suffix.

list + ed = listed
list + ing = listing

sad + ness

This is a tricky one.
"Does the root word have one syllable?" (yes)
"Does it have one vowel?" (yes, a)
"Does it have one consonant at the end?" (yes, d)
"Does the suffix begin with a vowel?" (NO!)
Do not use the 1-1-1 rule because "ness" does not begin with a vowel.